Molecular dynamics simulation and experimental study of the surface-display of SPA protein via Lpp-OmpA system for screening of IgG

Abstract

Staphylococcal protein A (SpA) is a major bacterial virulence factor of Staphylococcus aureus. S. aureus is capable of escaping from immune system recognition by the surface display of protein A. The SpA protein is broadly used to purify immunoglobulin G (IgG) antibodies. This study investigates the ability of the fusion of Lpp’-OmpA (46 − 159) to anchor and display five repeat domains of protein A with 295 residues length (SpA295) of S. aureus on the Escherichia coli cell surface to develop a novel bioadsorbent. First, the binding between Lpp’-OmpA-SPA295 and IgGFc and anticipation of this structure was investigated using molecular dynamics simulation. Then high IgG recovery from human serum by the surface-displayed system of Lpp’-OmpA-SPA295 performed experimentally. In silico analysis showed the binding potential of SPA295 to IgG after surface expression on LPP-OmpA. Surface-engineered E. coli displaying SpA protein and IgG-binding assay with SDS-PAGE analysis exhibited the high potential of the expressed complex on the surface of E. coli for IgG recapture from human serum which is applicable to conventional immune precipitation.